Random Color in objects using ProRender
The &quot;Random Color&quot; already produces a color, not a random numeric value like the missing Object Info node, so I think it doesn't play well with the ColorRamp node.
If I connect the &quot;Random Color&quot; output of the RPR Lookup node directly to Base Color on Principled BSDF, I get random colors as expected.

If you'd like to get back the palette control that ColorRamp offers you, you can pass the output of &quot;Random Color&quot; into the &quot;RGB to BW&quot; node (found under Converter) and then pass that output into ColorRamp as shown below.